Apparatus and method for leveling metal strip

ABSTRACT

An apparatus and method for leveling elongated metal strip includes pulling means for pulling the strip under tension in a longitudinal direction and flexing means for imparting flexing forces to the strip. The flexing means includes fluid pressure means for producing the flexing forces.

United States Patent 1191 Withrow I 1451 Aug. 13, 1974 APPARATUS ANDMETHOD FOR LEVELING METAL STRIP [75] Inventor: David A. Withrow,Willoughby,

Ohio [73] Assignee: Production Machinery Corporation,

Mentor, Ohio [22] Filed: Aug. 27, 1973 [21] Appl. No.: 391,559

Related US. Application Data abandoned.

[52] US. Cl. 72/163, 72/245 [51] Int. Cl BZ'ld 1/05 [58] Field of Search72/160, 163, 248, 246,

Primary Examiner-Milton S. Mehr Attorney, Agent, or FirmMeyer, Tilberry& Body s [57] ABSTRACT [63] Continuation of Ser. No. 196,985, Nov. 9,1971, -1

An apparatus and method for leveling elongated metal strip includespulling means for pulling the strip under 3 Claims, 6 Drawing FiguresPATENIEMH 31914 3.828.599

sum 1 or 2 INVENTOR. 04 W0 4. W/THRO W PATENTEB M191 SHEEIZBFZ 'LkkINVENTOR ATTORNEYS APPARATUS AND METHOD FOR LEVELING METAL STRIP This isa continuation, of application Ser. No. 196,985 filed Nov. .9, 1971, nowabandoned.

BACKGROUND OF THE INVENTION The present invention pertains to the art ofleveling elongated metal strip, and'more particularly to leveling suchstrip by the application of tensioning and flexing forces.

Elongated metal strip produced in a mill commonly has wrinkles, wavyedges and other imperfectionsflt is common to remove such imperfectionsby applying tension to the strip while passing the strip throughstaggered rolls. The combination of tension and flexing around the rollsstretches the strip beyond its yield point which permanently elongatesthe strip to remove the imperfections.

The rolls used for flexing the strip are preferably of small diameter toreduce the tension required for inducing permanent elongation. The rollsextend completely across the width of the strip and are normallysupported in end bearings. When small diameter rolls are used, thetension in the strip tends to deflect the rolls. However, if the workrolls are allowed to deflect, the quality of strip flattening will beseriously reduced. Conventional apparatus employs a large number ofsegmented backup rolls deployed along the length of the work rolls tominimize deflection of the work rolls. The requirement for a largenumber of backup rolls makes such apparatus very expensive. Furthermore,the backup rolls tend to emboss the work rolls after a pe riod of undertension.

It is a principle object of the present invention to provide an improvedapparatus and method for leveling metal strip.

It is also an object of the present invention to provide an apparatusfor leveling metal strip which uses a fluid film bearing. v t

It is another object of the present invention to provide an apparatusand method for leveling metal strip in a manner which, is moreeconomical and simpler than existing apparatus and methods.

It is an additional object of the present invention to provide anapparatus and method for leveling metal strip in a manner whicheliminates stripping of the strip.

It is a further object of the present invention to provide an improvedapparatus and method for leveling metal strip in a manner which providesenclosed support for the flex rolls to eliminate critical speedvibration of the flex rolls in high speed applications.

DESCRIPTION OF THE DRAWINGS The invention may take form in certain partsand arrangements of parts, certain preferred embodiments of which willbe described in this specification and shown in the accompanyingdrawings which form a part hereof.

FIG. I is a side elevational view of an apparatus for leveling strip andhaving the improvement of the present invention incorporated therein;

FIG. 2 is a partial cross-sectional elevational view of one lowerbending roll unit in FIG.- 1;

FIG. 3 is a simplified side elevational view showing the improvedarrangement of the present invention;

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings,wherein the showings are for purposes of describing certain preferredembodiments of the invention only and not for purposes of limiting same,FIG. 1 shows an apparatus A for flattening or leveling metal strip. Adrag bridle B includes rotatably driven rolls 10 and 12 through whichmetal strip C is trained as shown. A pull bridle D includes rotatablydriven rolls l4 and 16 through which strip C is also trained. Rolls 10and 12 of drag bridle B are driven in the direction of arrows 11 at alower speed than rolls 14 and 16 of pull bridle D which are driven inthe direction of arrows 15 so that strip C is under considerable tensionas it moves in the direction of arrows l7 and is elongated by thetensioning and flexing forces applied by apparatus A. It will berecognized that FIG. 1 is a simplified showing of a leveling apparatusand that additional components may be located between bridles B and D.For example, additional drag and pull bridles may be provided, as wellas a temper mill and pre-flex unit. Such arrangements are conventionaland have been omitted for simplicity of description.

In accordance with one arrangement, flexing means E ispositioned betweenbridles B and D for imparting flexing forces to strip C. Flexing means Ebends strip C as it passes therethrough. Flexing means E is designed tobend the metal back and forth in small radius bends. Flattening orleveling can be accomplished only by stressing the metal beyond itselastic range in order to produce permanent set. Therefore, the bendsproduced in passing through flexing means E are necessarily of smallradius.

In accordance with one arrangement, flexing means E includes upperbending roll units F and lower bending roll units G. Flexing means E mayalso include an upper roll unit H having rolls l8 staggered with respectto rolls 20 in lower roll unit I. Rolls 18 and 20 may be positioned toprovide vertually no flexing of strip C and simply serve to flatten thestrip. Roll units F, G, H and I may be adjustably positioned forvertical and lateral adjustment in a known conventional manner forproperly positioning the rolls.

Each upper bending roll unit F includes a roll 22 extending completelyacross the entire width of strip C and rotatably journaled in bearingjournal 24 mounted in bearing journal carrier 26. Each lower bendingroll unit G includes an elongated roll 22 extending completely acrossthe width of strip C and rotatably journaled in bearing journal 24carried by bearing journal carrier 26.

In accordance with one arrangement, each bearing carrier 26 of lowerbending roll units G includes a pair of oppositely disposedlongitudinally extending keys or projections 36 received in keyways orlongitudinal grooves 38 in bearing journal 24. Bearing carrier 26 isprovided with an enlarged bore 40 therethrough in alignment with athreaded bore 42 in bearing journal 24. An inclined hole 44 in bearingjournal 24 intersects threaded bore 42 at one end and longitudinalarcuate grooe 46 at its other end. Arcuate portion 50 in bearing journal24 is approximately 230 degrees and lies on the circumference of acircle. In one arrangement, arcuate portion 50 lies on the circumferenceof a circle whose diameter is around 2.502 inches and roll 22 has adiameter of around 2.500 inches. In other words, there is aroundtwo-thousandths clearance between the outer periphery of ,roll 22 andarcuate portion 50 of bearing journal 24. A nipple 52 extends throughbore 40 in bearing carrier 26 and is threaded into threaded bore 42 inbearing journal 24. Nipple 52 is connected through conduit 54 with theoutput end of a hydraulic pump 56 having an intake 58 positioned in sump60 and connected with pump 56 through filter 62.

In one arrangement, strip C is in contact with the outer periphery ofroll 22 over an arc of around .45 degrees so that strip wrap angle 66 is45 degrees. With this wrap angle, and a tension in strip C of around 800pounds per inch of width of roll 22, the resultant load indicated bynumeral 68 on roll 22 is around 500 pounds per inch of width. Oil havinga viscosity of -100 centipoises is supplied by pump 56 to groove 46 at apressure of -40 pounds per square inch. Oil then flows at a rate ofaround 1/l0th gallon per minute when roll 22 has a width of around 60inches. As strip C travels through apparatus A, roll 22 rotatesin thedirection of arrow 70 on a fluid film which develops between its outerperiphery and arcuate portion 50 of bearing journal 24. An induced loadcarrying film is created between the periphery of roll 22 and arcuateportion 50 when roll 22 rotates under applied load 68. For the valuespreviously given, a frictional torque of around 2.5 inch pounds per inchof width for roll 22 is developed during rotation thereof. As shown inFIG. 4, end plates 78 may be secured to bearing journal 24. The distanceacross the oppositely facing surfaces of plates 78 is slightly greaterthan the width of roll 22. Lubricant flowing into the end clearancesalso provides a fluid film thrust bearing. If desired, the ends of roll22 and plate 78 may be stepped or provided with spiral intake grooves todevelop a better hydrodynamic fluid pressure. I

. On bottom bending roll units G, it is also possible to provide anadditional longitudinal groove 80 extending along arcuate portion 50 ofbearing journal 24. Groove 80 is connected by hole 82 with threaded bore84 receiving nipple 86 extending through bore 88 in bearing carrier 26.Nipple 86 is connected with a higher pressure pump 90 through conduit92. High pressure pump 90 has its inlet 94 positioned in sump 60 throughfilter external pressure generation of the fluid film by hydrostaticeffect. In place of hydrostatic or hydrodynamic effect for producing thefilm it will also be recognized that pneumodynamic or pneumostaticlubrication may also be provided. The self-acting hydrodynamic bearingdescribed with internal pressure generation is the preferred embodiment.

It is also possible to provide upper bending roll units F with a highpressure inlet as described with reference to lower bending roll units Gso that upper rolls 22 will not be forced upward and seat under theforce of strip C acting thereagainst during strip stoppage.

As shown in FIG. 3, strip C also makes arcuate contact with upper roll22 over an angle of around degrees. Upper roll 22 is laterally displacedfrom lower roll 22 and positioned vertically downward so that strip C issharply bent as it passes through upper and lower rolls 22. Theperipheral portions of rolls 22 define flexing surface means whichextend traversely of strip C on opposite sides thereof. The arrangementdescribed relys upon viscosity and pressures of the load bearing film tosupply the flexing forces which bend strip C.

In accordance with another arrangement, as shown in FIGS. 5 and 6, apair of upper and lower flexing members 102 and 104 are positioned onopposite sides of strip C. Flexing members 102 and 104 replace bendingroll units F and G of FIG. 1. Each flexing member 102 and 104 is formedwith a stepped or radiused surface 106 and 108 facing the opposite sidesof strip C. Stepped surfaces 106 and 108 define a tortuous path throughwhich strip C is alternately flexed in one direction, then the other.Each stepped surface 106 and 108 is formed with longitudinally extendinggrooves 110 connected through holes 112 with nipples 114. Nipples 114are connected through conduits 54 with pump 56 of FIG. 1. The spacingbetween stepped surfaces 106 and 108 may be around four-thousandthsgreater than the thickness of strip C. The supply of lubricant betweenstepped surfaces 106 and 108, and the opposite sides of strip C,develops a fluid film sliding hearing so that strip C is flexed as itslides along the fluid film through the tortuous path provided bystepped surfaces 106 and 108. End plates 107 may be secured to flexing96. During line stops, when strip C is not moving, a suit- T able valvein conduit 92 may be opened and pump 90 energized to pump lubricatingfluid into the space between arcuate portion 50 and roll 22 so that roll22 will not seat during strip stoppage.

It will be recognized that upper bending roll units F are provided withlubrication in a manner described with reference to lower bending rollunits G. Lubricant is supplied to both upper and lower rolls 22immediately adjacent the area where the periphery of rolls 22 firstenter arcuate portions 50 in their direction of rotation. This insuresefficient development of a load carrying fluid film.

Instead of having a self-acting fluid bearing formed by hydrodynamiceffect, it will be recognized that additional ports may be provided toarcuate portion 50 for members 102 0and 104. The distance between theopposite facing inner surfaces of end plates 107 is slightly greaterthan the width of strip C.

It will be recognized that it is possible to use many different liquidlubricants including water in the arrangement described, and that wipersand splash guards may be provided for removing lubricant from strip Cafter it has passed through flexing means E and returning the lubricantto sump 60.

The improved roll mounting arrangement of the present invention iscapable of use in many applications other than tension leveling of metalstrip. For example, it may be used for metering lubricant or a coatingonto strip material. The improved roll mounting arrangement may be usedin any application requiring extremely low friction, such as a cage fora roller bearing or as a substantially frictionless fulcrum. The rollmounting arrangement is also useful in application where roll speeds arehigh and stability is essential.

Although the invention has been described with respect to certainpreferred embodiments, it will be recognized that obvious alterationsand modifications will occur to others skilled in the art upon thereading and understanding of this specification. The present inven-Having thus describedmy invention,l claim: 1. In an apparatus forleveling an elongated metal strip having a given width including meansfor pulling said strip under tension along a generally longitudinalpath, first and second generally cylindrical rolls extendingtransversely across said strip and onopposite sides of said path, eachof said rolls having a cylindrical outer surface concentric to alongitudinally extending axis, and means for rotatably supporting eachof said first and second rolls for rotation about said axes and incontact with said strip to define a flexing pattern for said strip as itmovesalong said path, the improvement comprising: said roll supportingmeanseach including a cylindrical recess extending parallel to said rollaxis and having a fixed inner cylindrical surface generally forcontinuously forcing a fluid into said space adjacent said firstcircumferentially spaced end whereby said fluid is dynamically forcedalong said space by rotation of one roll in said recess.

2. The improvement as defined in claim 1 including means for selectivelyforcing a fluid into said space at a position between saidcircumferentially spaced ends to apply a force between said inner andouter cylindrical surfaces.

3. In an apparatus for leveling an elongated metal strip having a giventhickness and width including means for pulling said strip under tensionalong a generally longitudinal path, and first and second generallyfixed elements positioned on opposite sides of said path and extendingtransversely across said strip, each of a said elements having means fordefining a flexing patmatching said outer cylindrical surface of one ofsaid rolls, said inner cylindrical surface being substantially less than360 to expose a position of said one roll and being slightly larger thansaid outer cylindrical surface to define an elongated arcuatespaceextending along said one roll and having first and secondcircumferentially spaced ends, said space having a generally uniformradial thickness determined by the difference in the size of said innerand outer cylindrical surfaces, said one roll being driven with respectto said inner cylindrical surface in a direction extending from saidfirst cir cumferentially spaced end of said space to said secondcircumferentially spaced end of said space,- and means tern for saidstrip as it moves along said path, the improvement comprising: a firstundulating surface on said first fixed element, a second undulatingsurface on said second fixed element and matching said first undulatingsurface, said first and second surface defining an undulating recessextending across said path a distance greater than the width of saidstrip and having a generally uniform thickness slightly greater than thethickness of said strip, first means for continuously forcing a liquidinto said recess between said first surface and said moving strip andsecond means for continuously forcing a liquid into said recess betweensaid second surface and said strip whereby said strip is supported onliquid as it is pulled through said undulating recess. y

1. In an apparatus for leveling an elongated metal strip having a givenwidth including means for pulling said strip under tension along agenerally longitudinal path, first and second generally cylindricalrolls extending transversely across said strip and on opposite sides ofsaid path, each of said rolls having a cylindrical outer surfaceconcentric to a longitudinally extending axis, and means for rotatablysupporting each of said first and second rolls for rotation about saidaxes and in contact with said strip to define a flexing pattern for saidstrip as it moves along said path, the improvement comprising: said rollsupporting means each including a cylindrical recess extending parallelto said roll axis and having a fixed inner cylindrical surface generallymatching said outer cylindrical surface of one of said rolls, said innercylindrical surface being substantially less than 360* to expose aposition of said one roll and being slightly larger than said outercylindrical surface to define an elongated arcuate space extending alongsaid one roll and having first and second circumferentially spaced ends,said space having a generally uniform radial thickness determined by thedifference in the size of said inner and outer cylindrical surfaces,said one roll being driven with respect to said inner cylindricalsurface in a direction extending from said first Circumferentiallyspaced end of said space to said second circumferentially spaced end ofsaid space, and means for continuously forcing a fluid into said spaceadjacent said first circumferentially spaced end whereby said fluid isdynamically forced along said space by rotation of one roll in saidrecess.
 2. The improvement as defined in claim 1 including means forselectively forcing a fluid into said space at a position between saidcircumferentially spaced ends to apply a force between said inner andouter cylindrical surfaces.
 3. In an apparatus for leveling an elongatedmetal strip having a given thickness and width including means forpulling said strip under tension along a generally longitudinal path,and first and second generally fixed elements positioned on oppositesides of said path and extending transversely across said strip, each ofsaid elements having means for defining a flexing pattern for said stripas it moves along said path, the improvement comprising: a firstundulating surface on said first fixed element, a second undulatingsurface on said second fixed element and matching said first undulatingsurface, said first and second surface defining an undulating recessextending across said path a distance greater than the width of saidstrip and having a generally uniform thickness slightly greater than thethickness of said strip, first means for continuously forcing a liquidinto said recess between said first surface and said moving strip andsecond means for continuously forcing a liquid into said recess betweensaid second surface and said strip whereby said strip is supported onliquid as it is pulled through said undulating recess.